This invention relates to a stable polymer dispersion in which the polymer constitutes the dispersed phase and a polyoxyalkylenepolyamine constitutes the continuous phase for use in polyurea reaction injection molding (RIM) or in the manufacture of polyurea foams, elastomers and the like.
Graft polymer dispersions in polyetherpolyol prepared by the in situ polymerization of ethylenically unsaturated monomers in the polyetherpolyol are known as a raw material of polyurethanes. See, U.S. Pat. Nos. 3,652,659; 3,875,258; 3,950,317; U.S. Pat. No. Re. 28,715 and U.S. Pat. No. Re. 29,014.
U.S. Pat. No. 4,286,074 to Davis et al. discloses a graft polymer dispersion in an amine-terminated polyoxyalkylene polyol, i.e. polyoxyalkylenepolyamine prepared by the in situ polymerization of ethylenically unsaturated monomer or monomers in the polyoxyalkylenepolyamine. The resulting graft polymer dispersion may be used in conjunction with conventional polyetherpolyol for the production of polyurethane products having improved mechanical properties.
Japanese Laid Open Patent Application (Kokai) No. 145711/83 corresponding to DOS 3200021 discloses a similar graft polymer dispersion in which the continuous phase is an aromatic amine-terminated polyetherpolyol which is prepared, in turn, by hydrolyzing a corresponding aromatic isocyanate-terminated polyether. This product is also useful as a raw material of polyurethane foams and the like.
It is postulated that the polymer grafted polyetherpolyol or polyoxyalkylenepolyamine forming the continuous phase in the prior art dispersions functions as a co-solubilizing agent which prevents the phase separation, fusion or solidification of polymer particles forming the dispersed phase. In contrast, a corresponding polymer separately produced by the solution polymerization will no longer make a stable dispersion in the polyetherpolyol or polyoxyalkylenepolyamine because they are not co-soluble in one another.
Although the above-cited U.S. Pat. No. 4,286,074 teaches that a wide variety of monomers are usable in the in situ polymerization method to produce a stable dispersion, only styrene, acrylonitrile and mixtures thereof have been actually tested.
It has been discovered that when performing the in situ polymerization in the polyoxyalkylenepolyamine, some ethylenically unsaturated monomers will produce a solid or semi-solid polymer mass which is no longer dispersible or miscible with the polyoxyalkylenepolyamine.
It is, therefore, a principal object of this invention to provide a stable dispersion of a wide variety of polymers in a polyoxyalkylenepolyamine liquid which does not undergo irreversible phase separation of dispersed polymer particles.
Other objects and advantages of the present invention will become apparent to those skilled in the art as the description proceeds.